This invention relates to contact bars for electrolytic cells provided with a spaced series of alternately arranged anodes and cathodes. The contact bars of the invention were particularly developed for use in electrolytic cells for the electrowinning of zinc, but may be used in cells for the electrolytic recovery of other metals in electrowinning or electrorefining processes.
The contact bars of the present invention have utility in processes for the electrolytic recovery of metals such as copper, cadmium, cobalt, lead, nickel, silver and zinc. For example, the contact bars have particular utility in zinc electrowinning processes of the general type described, for example, in expired U.S. Pat. No. 2,443,112, F. A. Morin, issued June 8, 1948. In processes of this type there are banks of electrolytic zinc cells, each cell containing electrolyte. Anode and cathode electrodes are disposed in parallel, equally spaced apart, arrangement in each cell, the anodes and cathodes alternating with one another. The anodes are insoluble in the selected electrolyte and are usually made of lead or silver-lead alloy. The anodes are provided with header bars which span the cell and are formed of an electrically conductive material such as copper. The cathodes are made of aluminum sheet material. Such sheet material lends itself to facile stripping of the zinc which is deposited at the cathodes. The cathodes are also provided with header bars formed of a conductive metal, usually aluminum.
In the apparatus in which the contact bars of this invention are intended to be used, the header bars, in the case of all the electrodes, extend outwardly on each side of the electrodes which they are intended to gravitationally support; and one of the extending portions on each header bar is provided on its underside with a notch in the form of an inverted V.
The contact bars of the invention support the electrodes and provide good electrical contact between the header bars and the contact bars, i.e., provide an intimate metal-to-metal contact so that a minimum of electrical resistance is offered to the passage of electric current between the contact bars and the notched portions of the header bars.
Our novel contact bar, which is of generally cylindrical configuration and has a spooled central section, provides for sloping-tangent contacts between (1) the grooves which form the spools and (2) the notches formed in the electrode header bars. The spools are created by cutting equally spaced grooves in the generally cylindrical contact bar. When the notches in the header bars are positioned in the grooves between the spools in the contact bar, the weight of the electrodes creates high pressure, sloping-tangent contacts, resulting in excellent transfer of electrical current between the header and contact bars.